The above mentioned U.S. patent application Ser. No. 08/839,663 "Material Penetrating Imaging Radar", incorporated herein by reference in its entirety, discloses a system using impulse radar and an array of transmitting and receiving antennas. The signal return from each transmitting antenna is sampled and digitized at each receiving antenna. The return signal is stored in a memory, and also can be stored in a data storage recorder for later processing.
A set of three dimensional pixels defines the search volume. For real time processing, the path delay from each transmitting antenna to each pixel and back to each receiving antenna is calculated. The contents of the memory elements corresponding to these delays are summed. This summation (integration) across the antennas is equivalent to real array beam processing.
The antenna array moves across and above the surface of e.g. the ground (or other volume to be searched). The signal returns relating to each pixel are also summed as the array moves across the ground. This approach provides synthetic aperture beams, which lends itself to parallel processing, which simplifies digital processor requirements.
In one disclosed application the transmitting and receiving antennas are arranged in a linear array which permits simple installation across the line of motion and is suitable for portable, mobile or airborne systems.